1. Field of the Invention
This invention relates to communication of data between a transmitting terminal and a receiving terminal. More particularly, it relates to a communication system which at least one of the terminals is a display terminal.
2. Description of the Prior Art
Communications wherein streams of coded data have been transmitted over communication linkages between transmitting terminals and receiving terminals have been in use for at least 75 years. In earlier conventional communications terminals, such as telegraphic equipment, the alphanumeric data was printed at the receiving end. In recent years, the receiving terminals have the capability of displaying the received alphanumeric data.
Where such conventional communicating terminals are functioning properly, they operate quite effectively. On the other hand, where there are communication problems either resulting in no alphanumeric data being received or erroneous alphanumeric data being received, or protocol incompatabilities, diagnoses of the problems has in the past often been time consuming and costly. There are available complex diagnostic apparatus which may be operated in association with terminals to diagnose problems. However, these are costly, require special set ups and special operator training. Very often such problems result in the non-use of the equipment until service engineers can visit the sites of the transmitting or receiving terminals and go through rather complex diagnostic routines. This results in problem communications equipment being "down" while the problem conditions exist.